I find the Thieves Guild and Dark Brotherhood feature some of the better questlines to be found in ESO. Which had me thinking what other compelling factions could be introduced to ESO to round out the Elder Scrolls experience. I'd personally like to see a vampire faction in ESO that's featured in one of the neutral areas of Cyrodiil such as County Skingrad or the Colovian Highlands. Right now, being a vampire seems fairly one note in terms of roleplaying and abilities. Vampire dailies in which you turn NPCs, vampire cattle assistants and a vampire lair could all be neat additions to a vampire questline. I suppose this idea could also be complementary to one of the chapters in the same way the Psijic order is to Summerset instead of being stand alone DLC as well.
What does everyone think of this idea and what other factions would you like to see added?